1. Field of the Invention
The present invention relates to medical instruments and more particularly to cutting means such as knives for surgical purposes, particularly a nozzle apparatus for performing such operations as dissection, resection and cutting by means of a jet of fluid.
2. Description of the Prior Art
Surgical means heretofore used include a steel knife, a radio knife, an ultrasonic knife, a laser knife, etc., and they are used effectively in accordance with purposes. However, the individual surgical means have the following advantages and disadvantages. In other words, while the steel knife is used frequently for its low cost and easiness for handling, its manipulation requires caution and skill since it cuts all the tissues equally. As a result, there is the danger of inadvertently cutting the blood vessels and losing a large amount of blood. While the radio knife is used widely owing to its relatively low cost and easiness for handling and has the effect of stopping the bleeding upon dissecting or cutting, there are disadvantages that the extent of thermal burn at the surgically treated part is large, that there is the danger of scalding during the manipulation, that from the apparatus point of view electromagnetic noise is produced in the power supply and so on. While the ultrasonic knife is capable of resecting the tissue of an affected part without damaging the cord-like things such as blood vessels despite its relatively high cost and being not used widely, there are disadvantages that its manipulation is complicated and troubles tend to occur in the suction system which is an auxiliary unit. While the laser knife is an excellent instrument in that it permits an operation in a non-contact manner, causes only a limited degree of damage to the surrounding areas of an affected part, has an haemostatic effect and a tissue transpiration effect and so on despite its relatively high cost, it is difficult to control the depth of dissection and resection and it is also impossible to selectively perform an operation on the tissues thus giving rise to the danger of causing a heavy loss of blood.
To overcome the drawbacks of the above-mentioned surgical means, recently methods utilizing a jet of pressurized fluid have been studied and put in clinical practice. These techniques can be understood by the prior art literatures such as the British Journal of Surgery Vol. 69, Page 93-94. With the methods of the type utilizing a jet of pressurized fluid, by adjusting the pressure and injection quantity within proper ranges, it is possible to separate the affected part from the adjacent parts without cutting the cord-like things such as the vascular tissue and to remove the separated tissue as well as the jet fluid from the treated part. The range of applications of these methods are so wide that the methods are effectively usable for the purpose of dissection and cutting with a high pressure of 10 MPa, for example, the purpose of ablation or the separation of the parenchyma tissue and cordlike things at a flexible part with a low pressure of 1MPa or less, the purpose of lavaging with a pressure of 1MPa or less and so on. The suitable fluids to be used include a physiological salt solution, adrenaline solution and other solutions exhibiting biological reaction. Further studies and experiments have been made on these methods in consideration of their wide range of applications and effects in that the methods are capable of effecting the cooling or heating simultaneously with any of the previously mentioned operations by adjusting the temperature of the fluid and so on. However, it has been found that when a jet of pressurized fluid impinges upon an affected part, the separated tissue of the affected part is mixed with the fluid and subjected to a violent agitation by the jet of pressurized fluid to form foam and give rise to such troubles as making it difficult to recognize the suitable position, contaminating the surrounding areas with the scattered foam and so on.